Substituted 3-aminopyrenes and process of preparing them



Patented Jan. 2, 1940 PATENT OFFICE SUBSTITUTED 3-AMINOPYRENES AND PROOESS OF PREPARING THEM Martin Oorell and Heinrich Vollmann, Frankfort-on-the-Main, and Hans Becker, Hofheim in Taunus, Germany, assignors to General Aniline Works, Inc., New York, N. Y., a corporation of Delaware o Drawing. Application February 10,1937, Sc-

4 Claims.

The present invention, relates to substituted 3-am1nopyrenes and to process of preparing them.

By the disubstitution of pyrene there are generally formed mixturesqo-f pyrene-,3,8-di-deriva- ,tivcs with the corresponding pyrene-3,10-diderivatives. V

The separation ofithe. constituents of these mixtures of disubstituted pyrenes involves inmost cases considerable losses since the differences in solubility of the isomerides are. very small and necessitate repeated fractional crystallization. The dinitropyrene, for instance, which may be obtained with a very good yield in the dinitration of pyrene has, already been described by several experts (of. Grabe, Annalen der Chemie, vol. 158, pages 292 to 293; E. Goldschmidt, Monatshefte der ,Chemie, Vol.2, page 580; and Jahota, Monatshefte der Chemie,, vol. 8, page 449) without the fact that it is a mixture having been observed. [By repeatedly extracting the crude dinitropyrene withboiling pyridine and repeated fractional crystallizationof the residue, we succeeded in separating pure 3,8-dinitropyrene (long, lustrous, light-yellow needles when crystallized from nitrobenzene; melting point 309 C.) fromthe mixture in moderate yield, whereas the 3,10- isomeride could not'be isolated in pure form.

We have found, that "mixtures of isomeric 3,8- and 3,l-pyrene-di-derivatives may be separated into their components in a relatively simple manner when at least one of the two substituents of the components is an amino-groupyi. c. When the mixtures contain compounds of the following scheme: I

rial No. 125,140. In Germany February 18,

wherein R represents a substituent, for instance, amino, acetyl amino, acetyl, chlorine or carboxyl. The difierence in solubility of these aminopyrenes is considerably greater than in the case of the corresponding nitropyrenes so that the isomerides may beseparated often by a single operation by treatment with solvents, for instance, with organic solvents, or, since also the salts of these amines-show'large differences in solubility, with aqueous strong acids. we have found that the 3,8-derivatives of pyrene of the above formula are less soluble than the 3,10-derivatives. As organic solvents there may be used with especially good results, for instance, alcohol, benzene, chlorobenzene, toluene, xylene,

pyridine. I

The individual aminopyrenes of this invention are useful as intermediates for the manufacture of dyestuffs. v 1 The following examples serve to illustrate the invention, but 'fthey are not intended to limit it thereto; the parts are by weight:

(1) 77 parts of dinitropyrene, melting at 280 C to 290 C., (being a mixture of 3,8- and 3,10- dinitropyrene, obtainable by nitrating pyrene in glacial acetic acid with 2 mols of nitric acid of specific gravity 1.5, or by nitrating finely divided 3-nitropyrene in water with nitric acid at 70 C. to 80 C.) in 550 parts of alcohol are treated at 70 C. in an autoclave provided with a stirrer with hydrogen in the presence of 2 per cent. of a nickel catalyst until the pressure no longer decreases. After cooling, the whole is filtered with suction, the alcoholic filtrate containing the 3,10- diaminopyrene and the solid residue containing the 3,8-diaminopyrene. The residual solid matter is treated with boiling xylene wherein the 3,8-diaminopyrene dissolves and the solution is freed from the nickel catalyst by filtration. The

3,8-diaminopyrene separates from the filtrate after cooling to room temperature in a nearly vpure state. After recrystallization from xylene or trichlorobenzene the 3,8-diaminopyrene is pure. It has a constant melting point of 232 C.

Thereby to 233 C. and dissolves in concentrated sulfuric acid to a colorless solution having a strong violet fluorescence.

The alcoholic filtrate is concentrated and the solid matter is recrystallized from toluene or xylene. The 3,10-diaminopyrene is thus obtained in the form of large prisms which have a constant melting point of 162 C. Good specimens of these crystals of both isomerides have a darkolive color whereas the color turns pure yellow when the crystals are triturated.

(2) 29.2 parts of dinitropyrene, melting at 280 C. to 290 C., are suspended in 250 parts of alcohol and a solution of 57 parts of sodium hydrosulfide of 30 percent. strength and 60 parts of water are added thereto. After about a quarter of an hour the same quantity of sodium hydrosulfide is again added andthe whole is boiled urt til the violet solution has become yellow. After cooling, the whole is filtered with-suction, .the solid matter is washed with water and dried. The yield amounts to 18 parts of crude diaminopyrene, melting at 160 C.

18 parts of this diaminopyrene are heated to boiling for a short time with 360 parts of sulfuric acid of 20 per cent. strength and 96 parts of water. The sulfate of ,3,8-diaminopyrene which is thus produced separates:in -:the.form 1 of light-grey needles. suction while hot, and the separatedv sulfate is rendered alkaline by meansiof. ammonia whereby cleavage of the sulfate occurs. The free amine is filtered with suction and dried. When recrystallized from xyleneitmeltsfat 230 C. to 232 C. and is pure 3,8-diaminopyrene.

The sulfate of the 3.10-diaminopyrene precipitates from the sulfuric acid filtrateon cooling; after renderingthesulfate alkaline by means of ammonia the free 3,10-1diaminopyrene is obtained which, afterrecrystallization, melts at 154 C. and is nearly pure.

(3) 60 parts of nitroacetaminopyrene.melting at 254 C. (mixtureof .3,8- and 3,10-derivatives, obtainable by nitrating v3-acetaminopyrene with 1 -mol of nitricacid in glacial aceticacid) in 300 parts of alcohol are treated with hydrogen at C. to C. in an autoclave provided with a stirrer .inithe presence of '3 per cent. of a nickel catalyst until the pressure remains constant. After cooling, the Whole is filtered withsuction and the solid matter is dissolvedin 660 parts of hot pyridine, the solution is filtered and the cold saturated filtrate thus obtained is diluted'with 300 partsofwater; after 2 to 3'hours standing the .3;8-aminoeacetaminopyrene separates which after recrystallization from a mixture of nitrobenzene and chlorobenzene (1:1) melts at 280 C. The aqueous pyridine filtrateis diluted with further 2000 parts of waterwhereby 3,-10-acetaniino-aminopyrene separates, and melts1at246 C. Byboiling with dilute'hydrochloric add these aminoa'cetaminopyrenes are saponified and the'isomeric diaminopyrenes are obtained in'purestate. l v

The process may also be carried. out by saponifying' the mixture of the nitroacetaminopyrenes with diluteihydrochloric.acid, catalytically reducing the mixture of the nitroaminopyrenes and, thereupon, fractionating" the free diamines, as described above.

(4) 42 partsof *chlor,onitropyrene,melting at 152 C. (a mixture of 3 ,8-:and.3-10-derivatives,

prepared by nitration of 3-chloropyrene-iin glacial The whole is filtered with gravity 1.5) in 200 parts of alcohol are treated at 60 C. to 70 C. in an autoclave provided with a stirrer with hydrogen in the presence of 2 per Y cent. of a nickel catalyst, until the pressure remains constant. After cooling, the whole reaction mass, in which the reduction product is contained partly in the form of a precipitate, is-

heated with addition of such a quantity of alco- 1101 that in the main only the catalyst remains undissolved in the hot alcohol. The alcoholic solution is filtered while hot. On cooling, an aminochloropyrene crystallizes in the form of long yellow needles which, on recrystallization, show a constant melting point of 142 C. and are the 3,8-chloro-aminopyrene. After standing for a prolonged time the 3,10-chloro-aminopyrene crystallizes from the alcoholic filtrate in the form v 10f yellow leaflets melting at 118 C.

(5) 115.,partsofnitro-acetylpyrene (a mixture of .3.,8-..and.3,10-derivatives, prepared from 3- acetylprene by nitration in glacial acetic acid with l mol of nitric acid, specific gravity 1.5)

are catalytically reduced in alcohol as described in Example 4. A

The mixture of s,sand 3,10-aminoacetyl pyrene thus obtained is separated by recrystal- 'lization from :alcohol, in which the 3,8-derivativeismore'diificultly soluble.- It crystallizes from chlorobenzeneinthe'form of orange-yellow prisms,

" melting at192 0., whereas the more easily solule -3-,10.-aminoace tylpyrene crystallizes in-the form.of.orangeyellow spears, melting at 136C.

' (.6) 24.6 .partsof .pyrene-3-carboxylic acid are finely-.triturated and suspended .in 750 parts of nitrob'enzene. At 75 C.,.a mixture of 7.5 parts of nitric acid (specific gravity 1.5) and..50 parts of nitrobenzeneis run in land the'whole is heated to. 170 'C. .to..180 IC. whereby the suspended ,mat-

ter dissolves entirely. On cooling, a mixture of probably 3.8-. and 3,1O-nitropyrene-carboXyIic acidscrystallizes therefrom in the'form ofyellow needles melting at.270-.C. to 285 C. They dissolvein concentrated sulfuric. acid-to an olivegreen and indilute caustic soda'solution to a yellow-red solution. r I

By-catalytical hydrogenation of theiaqueous solutionof the sodium salts of the .two nitro-pyrenecarboxylic acids with zth'e aidflof-nickel asolution of the corresponding;-amino-pyrene-carboxylic ,acids having alight-yellow fluorescence'is obtained, which; acids areprecipitated, by acidification with dilutehydrochloric acid, as salts in the form of thick" redbrownfiakes. On heating this suspension to boiling, the one isomeride dis- W solves to "a light-yellowssolution :and separates again. after filtration from the :residue which contains the'otherisomeride, in :theform of a viscousyellowishwmucilage. .gBy cautiously adding a-rdilute alkali, the fre'e 3-aminopyrene-10- carboxylic acid is obtained in"the=formof. yellowbrown "flakeswhich" dissolve in concentrated sulfuric a'cidto:a1 green-yellow solution having an intense green fluorescence and "in dilute caustic soda solution to a feebly yellow solutionhaving a grey-green fluorescence.

The red-brown residue separated from the hydrochloric solution by filtrationfis suspended in water and neutralized with dilute caustic soda solution. boxylic acid is obtained in the form of brown flakes and dissolvesrin concentrated sulfuric acid to a yellow solution having a blue-green fluorescence and a dilute caustic soda solution to a yellow solution having a"grey-gi"een fluorescence.

The isomeric 33-aminopyrene-8-car- We claim: '3. The compound of the formula: 1. The compound of the formula: 01

([JOQH: l EN m v h I IfIH2 NH: melting at 142 C. 4. The compound of the formula: being a compound which, when recrystallized COOH\/\ from nitrobenzene-chlorobenzene-mixture, melts at 280 C.

2. Individual substituted 3-aminopyrenes corresponding to the general formula X n v \/'-NH2 I forming brown flakes which dissolve in concentrated sulfuric acid to a yellow solution having a NH2 1 o rescence.

wherein X represents a substituent of the group consisting of acetamino, acetyl, chlorine and carboxyl.

blue-green fluorescence and in dilute caustic soda solution to a grey solution with green fluo- MAR'IIN' CORELL. HEINRICH VOLLMANN. I HANS BECKER. 

